Fountain pen structures



July 7, 1964 E. J. J. HENRIKSEN FOUNTAIN PEN STRUCTURES Original Filed Feb. 12, 1959 INVENTOR Ems? Johan km Hezzrz'kam ATTORNEY5 United States Patent 3,139,864 FOUNTAIN PEN STRUCTURES Ernst Johan Jens Henriksen, 1 Alpenstrasse, Lucerne, Switzerland Original application Feb. 12, 1959, Ser. No. 792,824. Divided and this application Dec. 6, 1961, Ser. No. 157,533

Claims priority, application Denmark July 6, 1953 Claims. (Cl. 12042.4)

This application is a division of my copending application Serial No. 792,824, filed February 12, 1959, now abandoned, which in turn is a continuation-in-part of my copending application Serial No. 551,363, filed December 6, 1955, now abandoned, which in turn is a continuationin-part of Serial No. 421,934, filed April 8, 1954, now abandoned, the latter being a continuation-in-part of Serial No. 705,927, filed October 26, 1946 (now Patent No. 2,678,634).

This invention relates to fountain pen structures and more particularly to ball point pen structures.

It is one of the objects of the invention to provide means affording elfective protection of the ink column in a fountain pen reservoir against deterioration and other influences by air or like media through which said ink column is fed toward the ballpoint.

It is another object of the invention to provide means facilitating observation and reading of the amount of ink consumed or available in the reservoir of a fountain pen during use of same.

It is still a further object of the present invention to provide means ensuring continuous and uniform flow of ink from said reservoir to the discharge end thereof at the ball point and avoiding flowing out or escape of the ink from said reservoir in a direction different from that extending toward said ball point.

Yet a further object of the invention resides in the provision of means contributing to an improved writing implement which may be inexpensively manufactured by mass production methods, is pleasing in appearance, whose operation is very efiicient and smooth, and in which the use of ink contained in its reservoir up to its exhaustion is rendered possible due to certain provisions which also permit the user to recognize from without the fountain pen implement, when such ink exhaustion will be and/ or is reached.

Still another object of the invention is to provide means enabling the employment of any type of ink (paste, fluid, semi-fluid) of predetermined viscosity in fountain pens of the aforesaid type and the possibility of adjusting the composition of a follower for the column of said ink in accordance with the type of the ink used therefor.

Still another object of the present invention is to provide means conducive to the employment of a plug or like follower element which readily adjusts itself to the diameter of the ink reservoir and whose length may be varied so as to become an indicator for the ink column in the reservoir during the operation of the fountain pen.

It is still another object of the present invention to provide means affording ready adaptation of the follower mass to changes in temperatures, whereby the latter does not lose its slidability along the wall of the ink reservoir and may readily adjust itself to fountain pens equipped with capillary, as well as with tubes of relatively wide diameter.

Still another object of the present invention is to provide means permitting the application of a feed pressure onto the ink column of the reservoir through the intermediary of a follower mass or body which will withstand the pressure and will protect the ink column from contact with the gaseous medium which exerts such pressure.

The present invention further consists of other novel features and details of construction, all of which will appear more fully from the following detailed description and accompanying drawing:

FIG. 1 shows a fountain pen structure with reservoir in section made in accordance with the invention;

FIG. 2 is a longitudinal sectional view of the upper part of a fountain pen reservoir embodying a modified form of the invention;

FIG. 3 is a sectional view of a fountain pen having inserted therein a reservoir structure in somewhat modified form and in accordance with the invention;

FIG. 4 is a fragmentary sectional view of a reservoir made in accordance with the inveniton;

FIG. 5 shows a reservoir in section embodying the invention in a still further modified form;

FIG. 6 is a longitudinal sectional view through another modified embodiment of the invention; and

FIG. 7 shows a fragmentary sectional view of a fountain pen reservoir still further modified in accordance with the invention.

Referring now more particularly to the attached drawing there is disclosed a fountain pen reservoir 10 having a plurality of meander-shaped channels 11 separated by intermediate walls or partitions 12 and interconnected through upper and lower channel recesses 13 and 14, the latter extending into respective body end pieces 15, 16, so as to constitute an uninterrupted ink feed to conduit 17. Conduit 17 and channels 11, in this particular instance, are of sufficiently reduced dimension which prevents ink from flowing out of the reservoir in any position of the fountain pen.

In this embodiment, the channels or passageways 11 forming the ink reservoir may be arranged directly within the solid handle portion 15 of the writing instrument Ill as shovm, whereby manufacturing of such writing instruments may be simplified. Moreover, when this ink reservoir is constituted by a series of channels as in the em bodiment shown in FIG. 1, the advantage is achieved, that gravitation will not substantially alter the position of the ink contained in the ink reservoir or channels, and the ink column 19 is kept in perfect position, thereby pro viding an eflicient feed to the ball tip 18 of the forward end of thepen. In the embodiment of FIG. 1 this feed occurs through the ink feeding conduit 17 toward the conical front end piece 16a containing a seat for the ball 18, as is well known in the art.

FIGv 1 shows ink column 19 located in the end channel portion 17. Above said ink column 19 there is disposed a follower or seal 20 consisting of a viscous or flow resistant pulpy mass, which is immiscible with ink, which is of a substance other than ink and which may preferably be composed of or comprise for its major part, a mineral oil thickened with a metallic soap, such as aluminum stearate.

As another example for a soft, plastic or flow resistant pulpy mass may be mentioned petroleum jelly or soft or semi-hard parafiin (petrolatum), known under the registered trademark Vaseline, with certain chemical additions which result in a follower mass, capable to readily conform to the shape and any dimensions of the feed channel or channels, adheres to the end of the ink column, follows the latter without substantially adhering to the inner wall surface of the feed channel or reservoir. This mass may further be colorless and the density of the mass may be substantially the same, higher or lower than the viscosity of the ink, forms a perfect seal against penetration of air or other gaseous medium to or contact with the ink column proper in the feed channel, so that the ink be it liquid, semi-liquid or pasty, will not deteriorate or be subjected to evaporation through the influence of the air or like medium. The mass itself should withstand readily changes in temperatures and will not undergo substantial changes upon the exposure to the atmosphere or like gaseous medium, even if under pressure.

If the ink is made from or based on a non-hygroscopic oil, a substance consisting of-gelatine suspended in water, such as agar-agar, may be used as a follower. A substance containing a cellulose derivative in water suspension may also be used.

However, such type of follower must be protected from contact with the air (as such follower would otherwise deteriorate and dry out under water evaporation), which will be etfectuated by applying a viscous layer of mineral oil substance onto the layer of said water-based substance. Thus, the follower may consist of a plurality of layers of different substances. One of said substances may also be capable of cleansing the wall of the reservoir.

In FIG. 2 there is shown a modified embodiment of the invention, disclosing a follower 30 within an ink reservoir 31, which contains an ink column 32. The end 33 of the reservoir 31 is closed and within the space 34 of the upper end of ink reservoir 31 there is defined a chamber 35 into which is dischargeable a gas or other means adapted to exert a suitable driving pressure onto the follower 30 and through it on the ink column 32 within the reservoir 31. Follower 30 may be of the same substance as herein disclosed with respect to follower 20 of FIG. 1.

FIG. 3 shows an embodiment of the invention in which the fountain pen 41 contains a movable reservoir 42 filled with ink 43. At the upper end 43a of the ink column 43 there is positioned a follower 40 of suitable mass herein referred to. Reservoir 42 further contains a piston 44 mounted on a rod 45, which in turn is rigidly connected to a cap 46. This cap 46 is fastened by screw threads 47 to the outer barrel 48 of the fountain pen 41. Between the upper inner face 49 of the cap 46 and the upper end 42a of inner reservoir 42, there extends a compressible spring member 50 wound around stem or rod 45, the latter being fixedly attached in the upper end wall 49 at 51.

End wall 42a of reservoir 42 has a passageway 42]) for guiding stem 45 through end wall 42a. Thus, a resilient connection between piston 44 and the reservoir 42 slidably mounted within barrel 48, is achieved.

When the ball 52 is pressed firmly against the writing paper, as will often be the case during writing, the reservoir 42 will be moved relative to the barrel 48 and the piston 44. This movement will amount to, or will be equivalent to, a pumping operation which will enable a sufiicient driving pressure to be maintained above the follower 40, and consequently on the surface of the ink column 43. The somewhat curved tip end 53 of ink reservoir 42 is reciprocably movable through suitable opening 54 of barrel 48 of the fountain pen.

It is to be observed that piston 44 is provided with a flap or other valve (not shown), which will allow compressed air to be pressed into the space or chamber 55 without allowing said compressed air to escape from space 55.

A similar function for establishing air pressure upon the follower on an ink column contained in barrel 56 is shown in FIG. 4, wherein the upper end of the latter is closed by means of a cap 57, having a cylindrical bore which communicates with an air intake 58. Knob or press button 59 is slidably mounted within bore 58a and is actuatable by a spring 60.

The narrow clearance between knob 59 and bore 555a in cap 57 will admit a sufiicient amount of air to be pumped into the interior 56a of barrel 56 when moving knob 59 against the action of the spring 60, whereby a suitable driving air pressure is attained against the openended ink reservoir (not shown). A suitable air pressure is also applied to the follower for the ink column in a way similar to that described in connection with the embodiments of FIGS. 2 and 3.

While FIG. 3 shows a fountain pen reservoir of relatively large diameter (in comparison with the feed channel shown in FIG. 1) the reservoir of fountain pen 31 as seen in FIG. 2 may have a diameter similar to that of the reservoir disclosed in FIG. 3 or FIG. 1, as desired.

FIGS. 5 and 6 also show fountain pen structures with inner reservoir diameter of reduced size or dimension or of larger dimension herein referred to with respect to FIG. 3.

In FIG. 5 there is shown a reservoir 70, preferably of transparent material, such as suitable plastic or plastic composition, which at its lower end 71 receives a tip member 72 terminating in a writing ball tip 73 of known construction. Reservoir '70 contains an ink column 74, an intermediary plug 75 and an end plug 76. The ink level 74a of the ink column 74 is in contact with the adjacent end of plug 75, which may be suitably colored, serving the purpose of determining and indicating the position of level 74a of the ink column from without the reservoir.

Above plug 75 is positioned plug 76 made from a viscous pulpy mass. A special marking 77 is provided on the outer surface of ink reservoir 70 and a predetermined distance from ball tip 73 so as to aid in indicating whether ink column 74 with its level 74a originally assumed the condition when Writing or use of the ink reservoir 70 is being started. It will be further observed that the combined volumes of plugs 75 and 76 correspond approximately to the volume of the ink column 74 extending between the markings 77 and 74b, which is the total ink volume to be effectively used before the reservoir is emptied.

FIG. 6 shows a fountain pen 80 composed of the following main portions: upper barrel portion 81, lower barrel portion 82, inner reservoir 83 with end member 34 which terminates in a ball tip 85 of suitable dimension. Upper and lower barrel portions 81 and 82 are connected in any suitable manner to a projecting annulus 86 forming an integral part of the reservoir 83 and made together with the latter from suitable, transparent plastic material. Reservoir 83 contains a column of ink 87 and a plug member 88 thereon, whose length corresponds to that of the ink column 87, the latter reaching approximately up to said annulus 86, which enables observation of the ink column 37 and its follower 38 from without the barrel portions of the fountain pen.

Reservoir 83 has the upper air space 89 which communicates with the air channel 90 provided in the end of barrel portion 81. This air chamber 89-90 admits air to follower 88 in a manner similar to that of follower 20, which is in contact with ink column 19.

It will be further understood that the inner diameter of tubular reservoir 83 may be of capillary size like channel 17 of FIG. 1 or may be of larger diameter as reservoir 42 disclosed in FIG. 3.

In FIG. 7 there is shown a portion of reservoir having the space for an ink column 96, follower 97 having a reduced diameter with respect to the diameter of the reservoir containing the ink column 96 and having further an enlarged follower portion 98 directly in contact with the end of the ink column 96. Consequently, the diameter of the ink reservoir proper containing ink column 96 is larger than that of follower portion 97. Due to such changes in volume and cross sections a speedier movement of the upper end 97 of the follower is achieved whereby better reading facilities for the level of the ink column at 96 outside the ink reservoir may be facilitated. In such a structure the substance forming the follower seal or plug 97-98 should be rather in liquid state so that the follower may readily fill out the respective spaces at 97 and 98. It will be obvious, therefore, that the pen described contains means therein to prevent the plug follower from flowing out of the reservoir when the pen is tilted away from its normal writing position.

In the disclosure hereinabove set forth, the substance for the follower mass is to be chosen in accordance with the type of the ink used and in accordance with the respective dimension of the ink reservoir, whereby the follower mass must be made from a substance other than the writing ink of the ink column, is substantially not miscible with said writing ink and has the property of readily following the ink column through the reservoir without regard to the shape and diameter of the latter.

The follower mass should be sufiiciently viscous and pasty or pulpy, so that it will not be affected or will undergo changes caused by the surrounding atmosphere and its temperature such materials as described above and their functional equivalents will be referred to as nonsolid materials.

In special cases it is preferable to employ an intermediate layer or follower plug which contains, for its major part, gelatine or similar water-based substance, such as gum tragacanth, if the ink substance contains mineral oil or any other kind of non-hygroscopic oil. The viscous pulpy mass, as the main follower, is then in contact with such intermediate follower and protects the latter as well as the ink column from contact or mixing with the air or similar gaseous medium. This main follower mass may then consist of a mineral oil derivative, such as paraflin or wax, with the addition of one or more metal soap ingredients for regulating the physical consistency of the main follower. It has been found, in practice, that approximately 80 to 90 percent mineral oil may be thickened to suitable viscosity by means of a metallic soap, such as aluminum stearate, forming the remainder of the viscous pulpy mass. Such follower mass may be used in capillary reservoir tubing as well as in reservoirs with relatively large diameters.

The follower mass may further comprise a plurality of layers having different properties, one of which forming or containing cleaning material serving as a solvent for the ink film remaining in contact with and obstructing the visibility through the Wall of the reservoir. Such follower layer may contain a solvent, for example, alcohol, if the ink contains alcohol or other easily evaporating solvent, which must be protected from contact with the air by a layer of a viscous pulpy mass, as hereinabove disclosed.

If one of the layers of the follower mass is employed as an indicator or control layer and if such layer adheres to the wall of the reservoir to a larger extent than the rest of the follower, such layer may be composed of ricinolic or castor oil thickened with a metallic soap, such as aluminum stearate, which layer contributes to the slowing down of the movement of the ink mainly towards the ball point and thereby regulates the ink feed.

If the intermediate layer is composed of ink approaching the composition of the column of the ink but preferably of a different color than the latter, then such intermediate ink layer must also be protected against deterioration or oxidation by contact with air or other gaseous medium having access to the ink reservoir, by the employment of a main follower mass made from a viscous pulpy substance, such as hereinabove referred to.

In all these instances, the ink follower, either directly or indirectly, contributes to an even and uniform flow of the ink past the ball point or tip since the ink follower effectively protects the ink column and intermediate follower layers against undesired influences of the air. The follower, according to the invention, may also serve the purpose of indicating the volumn and extent of the ink column within the reservoir.

The follower may further consist of several layers of the same mass but having colors different from each other so that one portion of the follower is an indication for the complete filling of the reservoir with ink, whereas another color indicates that the reservoir is only half filled and needs replenishment.

It ensues from the aforesaid disclosure that the follower or plug mass is chosen according to the chemical composition and physical properties and viscosity of the ink used in the reservoir.

It is always required that the follower mass does not flow out of the air inlet of the reservoir, and that escape of ink from the reservoir past the follower mass along the wall of the reservoir be effectively avoided.

A further requirement is that the mass for the follower not only conforms to the diameter or cross-section of the reservoir, but that size and height (length) of the follower are selected so as to slide easily along the reservoir and that, if some of the follower mass would be deposited as an extremely fine film on the wall of the reservoir during operation a sufficiently long layer of follower mass remains on the column of ink until or even if the reservoir becomes depleted.

The follower should be composed of such mass that it not only avoids commingling with the ink substance used, but should also prevent any disolution of the latter; furthermore the viscosity or flow resistance of the follower mass must withstand to a marked degree exposure to tropical as well as to arctic climate, thus does not lose its capability of sliding along and within the reservoir, of readily following the end surface of the ink column and remains substantially non-melting. The follower mass may be a lubricant, used for self-lubrication of bearings, forming a gel and withstanding temperature conditions above 350 F.

If the suction effect created during writing is or becomes insufficient for the lowering of the level of the ink column, the movement of the follower mass may be infiuenced by additional feed pressure, as hereinabove described with respect to FIGS. 3 and 4 and the follower mass must necessarily withstand such pressure.

In order to overcome any difficulty with respect to any colored deposit during lowering of the level of the ink column along the transparent wall of the reservoir, the follower is so dimensioned that the volume of the latter is equal to or even larger than the volume of the ink column, to be used up during the writing operation, whereby the upper end of the follower becomes discernible or viewable in the reservoir (FIG. 6).

The height of the follower may be chosen so that, if the wall of the reservoir is provided with several gradations extending between the level of the ink column when said reservoir is filled and a level of said column at which depletion of the ink column and complete emptiness of the reservoir occur, the latter or end gradation or marking must not necessarily be indicated at the limit point or point of separation between ink and follower.

It is, however, essential that the height of the follower or plug coincides with the distance of the upper level of the ink column from the inner end of the ball point when the ball point pen is completely filled (FIG. 5). It may become also important to observe whether the follower mass will leave any film deposit on the inner wall surface of the reservoir and such loss of follower mass must be compensated for by suitable increase of the height of the follower mass.

If the following is composed of aplurality of layers, as hereinabove set forth, the upper most layer thereof must be sufficiently long and also suitably viscous that the remainder of the follower as Well as the ink will not flow out of the reservoir, even if the uppermost follower layer will leave fine film deposits on the reservoir wall.

In building up the follower in layer formation care may be taken to employ a lowermost, relative thin layer on the follower for the purpose of preventing any influence of the ink on the follower mass during long storage and under extreme climatic conditions, as herein referred to.

The uppermost end of the follower mass as seen in FIGS. 5 and 6, may be solely modified as to its physical and flow characteristics, so that it produces a kind of braking eifect, when this end during sliding movement 7 of the follower leaves behind a very thin film on the inner wall of the reservoir and thus to some degree influences and regulates supply of ink at the writing or ball point end.

The film producing end layer of the follower mass should not be able to mix with any adjacent layer or layers of the remainder of the follower and must be of such consistency that at normal room temperature escape or flowing out along the wall of the reservoir will be effectively prevented. Silicon oil or grease, as well as mineral oil or grease as a follower mass is considered useful for such purpose.

It can thus be seen according to the invention that improved means are provided whereby the fluid or semipasty ink contained in fountain pens is protected from contact with the air and is at the same time prevented from flowing out through the air intake of the ink reservoir.

Thus, a lid or follower is slidably mounted within the ink reservoir adjacent the surface of the ink or paste contained therein. This lid or follower which may be a cylindrical body of small weight, for instance, a semipasty body of a composition of paraflin or may consist of a substance having approximately the same viscosity as the ink but of such nature that it is unable to mix therewith, is adapted to prevent the air admitted through the air intake to contact the surface of the ink and also to prevent the ink from flowing from the reservoir into the interior of the barrel.

Alternatively the lid or body may consist of a cylindrical body of resilient material, wax, paraffin or of a layer of a viscous or pulpy mass of substantially the same viscosity as the ink and having a color which is distinctly different from the color thereof, thereby providing means for indicating to the user when the ink reservoir is approaching exhaustion which will become apparent from the change of color on the writing paper, when the pulpy mass above the ink column is extracted through the ink feeding channel to the writing ball.

The ball tip fountain pen may comprise a pulpy mass within said reservoir and wherein said lid slidably mounted within the said reservoir is a layer of a pulpy mass which may have substantially the same viscosity as the pulp ink adjacent the surface thereof, said pulpy mass being of such nature that it is unable to mix with said ink.

Reverting again to FIG. of the aforesaid disclosure, the reservoir 70 which may be of capillary dimensions, if desired, may contain a main ink column 74 of conventional ball pen writing ink with an ink slug 75 which is in contact at 74a with said ink 74. Ink slug 75 may have a color distinctly different from that of the ink column 74, whereby ink slug 75 serves to indicate to the user that the pen is nearing exhaustion, and that a new reservoir of ink must be supplied to the fountain pen. When the ink of the ink column has been almost used up, the specially colored ink slug 75 (which may be of the same ink composition as ink column 74) will approach and make contact with the writing ball and will be transferred onto the writing paper to thereby provide the aforesaid indication.

Above ink slug 75 is then positioned a protective layer 76 made from any of the suitable follower substances hereinabove mentioned capable of protecting the ink slug 75 and ink column 74 against deterioration by air or other gaseous medium. It is, of course, understood that layer 76 may be of different dimensions and may be of shorter length than shown in FIG. 5. Protective follower or layer 76 may be, e.g., a greasy product derived from the distillation of petroleum, such as petroleum jelly, semipasty paraffin and like derivative having or affording the desirable properties (non-drying upon exposure to air, etc.) hereinabove set forth.

Likewise and for the same purpose as set forth hereinabove, plug member or layer 88 of FIG. 6 may consist of ink of any suitable composition (oil base, water base, and the like), but differ in color from the ink constituting ink column 87, thus also indicating the exhaustion of the latter as soon as layer 88 reaches ball tip 85.

In this case, ink plug 88 must have a composition different from that of ink column 87 and must be substantially imiscible therewith. It also must be impervious to air or a gaseous medium to effectively protect the ink column 87.

It is to be noted that the ink plug may be a fluid or pasty substance, but of such composition that it will not readily mix with the ink, although such substance may have the same consistency as the ink of the ink column. Consequently, the plug may consist of a plastic or plasticized substance, having such characteristics that it can adjust itself to the form or cross section of the reservoir while it is sliding therein. For instance, the plug may consist of a spongy material impregnated with a substance which serves to reduce the friction between the plug and the wall of the reservoir. In any event the plug will not permit the ink in the reservoir to get in direct contact with the ambient air as the reservoir is vented.

To employ an ink plug which is only different in color from the remainder of the ink column with which the ink plug is to cooperate, would only be possible, if such ink plug would have the same high viscosity as that of the ink of the ink column, as otherwise the ink plug would quickly diffuse with the remainder of the ink column. Protection of ink plug and ink column of substantially the same high viscosity against influence from the ambient air may, however, not be attained, unless a further plug according to this invention is used, which is in contact with the first-mentioned ink plug, the latter functioning as an indicator for the user of the fountain pen to show that the remainder of the ink column is exhausted.

As an example of an ink in which the present invention finds particular utility, applicant has found that a glycolbased ink absorbs moisture from the air upon exposure to air and that such moisture causes the ink to harden or solidify. Therefore, a pen with a reservoir filled with such glycol-based ink will cease writing because the exposed surface of the ink would harden to a solid mass and the ink could no longer flow. A plug follower formed from a mineral oil based ink serves to protect the glycol-based ink from exposure to air and prevent hardening thereof. The mineral-based ink is immiscible with the glycol-based ink and is not itself subject to hardening or other deterioration upon exposure to air. A suitable glycol-based ink has the following composition in parts by weight:

Triethylene glycol 100 Beta naphthol 32 Azosol Fast Black MA l2 Azosol Brilliant Blue B It will be readily apparent that other glycols, such as diethylene glycol, propylene glycol and other alcohols and polar solvents may be substituted wholly or in part for the triethylene glycol. The beta naphthol acts to solubilize the dyes to some extent. The Azosol dyes above specified are made by General Dyestuffs Corporation and are conventional type ink dyes. If desired, a detergent may be added to the ink to further assist in holding the dyes in solution and to impart smoother writing action to the ball. The oil-based ink may be a different color from the main body of ink, or it may be the same color to thereby increase the capacity of the pen.

It is important that the follower material is different from the ink not only in composition but also in nature. This also applies to the aforesaid adjoining layers of plugs. If, for instance, one follower plug consists of two distinctly colored layers of the same material, i.e., petroleum jelly, these layers would be different, but the difference would only be as to the colors of the dyestuffs, but the nature of both layers would be the same and they would, therefore, not be immiscible. According to the invention,

In the disclosure hereinabove set forth, the substance for the follower mass is to be chosen in accordance with the type of the ink used and in accordance with the respective dimension of the ink reservoir, whereby the follower mass must be made from a substance other than the writing ink of the ink column, is substantially not miscible with said writing ink and has the property of readily following the ink column through the reservoir without regard to the shape and diameter of the latter.

The follower mass should be sufficiently viscous and pasty or pulpy, so that it will not be affected or will undergo changes caused by the surrounding atmosphere and its temperature such materials as described above and their functional equivalents will be referred to as nonsolid materials.

In special cases it is preferable to employ an intermediate layer or follower plug which contains, for its major part, gelatine or similar water-based substance, such as gum tragacanth, if the ink substance contains mineral oil or any other kind of non-hygroscopic oil. The viscous pulpy mass, as the main follower, is then in contact with such intermediate follower and protects the latter as well as the ink column from contact or mixing with the air or similar gaseous medium. This main follower mass may then consist of a mineral oil derivative, such as paraflin or wax, with the addition of one or more metal soap ingredients for regulating the physical consistency of the main follower. It has been found, in practice, that approximately 80 to 90 percent mineral oil may be thickened to suitable viscosity by means of a metallic soap, such as aluminum stearate, forming the remainder of the viscous pulpy mass. Such follower mass may be used in capillary reservoir tubing as well as in reservoirs with relatively large diameters.

The follower mass may further comprise a plurality of layers having different properties, one of which forming or containing cleaning material serving as a solvent for the ink film remaining in contact with and obstructing the visibility through the wall of the reservoir. Such follower layer may contain a solvent, for example, alcohol, if the ink contains alcohol or other easily evaporating solvent, which must be protected from contact with the air by a layer of a viscous pulpy mass, as hereinabove disclosed.

If one of the layers of the follower mass is employed as an indicator or control layer and if such layer adheres to the wall of the reservoir to a larger extent than the rest of the follower, such layer may be composed of ricinolic or castor oil thickened with a metallic soap, such as aluminum stearate, which layer contributes to the slowing down of the movement of the ink mainly towards the ball point and thereby regulates the ink feed.

If the intermediate layer is composed of ink approaching the composition of the column of the ink but preferably of a different color than the latter, then such intermediate ink layer mnst also be protected against deterioration or oxidation by contact with air or other gaseous medium having access to the ink reservoir, by the employment of a main follower mass made from a viscous pulpy substance, such as hereinabove referred to.

In all these instances, the ink follower, either directly or indirectly, contributes to an even and uniform flow of the ink past the ball point or tip since the ink follower effectively protects the ink column and intermediate follower layers against undesired influences of the air. The follower, according to the invention, may also serve the purpose of indicating the volumn and extent of the ink column within the reservoir.

The follower may further consist of several layers of the same mass but having colors different from each other so that one portion of the follower is an indication for the complete filling of the reservoir with ink, whereas another color indicates that the reservoir is only half filled and needs replenishment.

It ensues from the aforesaid disclosure that the follower or plug mass is chosen according to the chemical composition and physical properties and viscosity of the ink used in the reservoir.

It is always required that the follower mass does not flow out of the air inlet of the reservoir, and that escape of ink from the reservoir past the follower mass along the wall of the reservoir be eifectively avoided.

A further requirement is that the mass for the follower not only conforms to the diameter or cross-section of the reservoir, but that size and height (length) of the follower are selected so as to slide easily along the reservoir and that, if some of the follower mass would be deposited as an extremely fine film on the wall of the reservoir during operation a sufficiently long layer of follower mass remains on the column of ink until or even if the reservoir becomes depleted.

The follower should be composed of such mass that it not only avoids commingling with the ink substance used, but should also prevent any disolution of the latter; furthermore the viscosity or flow resistance of the follower mass must withstand to a marked degree exposure to tropical as well as to arctic climate, thus does not lose its capability of sliding along and within the reservoir, of readily following the end surface of the ink column and remains substantially non-melting. The follower mass may be a lubricant, used for self-lubrication of bearings, forming a gel and withstanding temperature conditions above 350 F.

If the suction efiect created during writing is or becomes insufficient for the lowering of the level of the ink column, the movement of the follower mass may be infiuenced by additional feed pressure, as hereinabove described with respect to FIGS. 3 and 4 and the follower mass must necessarily withstand such pressure.

In order to overcome any difiiculty with respect to any colored deposit during lowering of the level of the ink column along the transparent wall of the reservoir, the follower is so dimensioned that the volume of the latter is equal to or even larger than the volume of the ink column, to be used up during the writing operation, whereby the upper end of the follower becomes discernible or viewable in the reservoir (FIG. 6). i

The height of the follower may be chosen so that, if the wall of the reservoir is provided with several gradations extending between the level of the ink column when said reservoir is filled and a level of said column at which depletion of the ink column and complete emptiness of the reservoir occur, the latter or end gradation or marking must not necessarily be indicated at the limit point or point of separation between ink and follower. It is, however, essential that the height of the follower or plug coincides with the distance of the upper level of the ink column from the inner end of the ball point when the ball point pen is completely filled (FIG. 5). It may become also important to observe whether the follower mass will leave any film deposit on the inner wall surface of the reservoir and such loss of follower mass must be compensated for by suitable increase of the height of the follower mass.

If the following is composed of aplurality of layers, as hereinabove set forth, the upper most layer thereof must be sufiiciently long and also suitably viscous that the remainder of the follower as well as the ink will not flow out of the reservoir, even if the uppermost follower layer will leave fine film deposits on the reservoir wall.

In building up the follower in layer formation care may be taken to employ a lowermost, relative thin layer on the follower for the purpose of preventing any infinence of the ink on the follower mass during long storage and under extreme climatic conditions, as herein referred to.

The uppermost end of the foHower mass as seen in FIGS.- 5 and 6, may be solely modified as to its physical and flow characteristics, so that it produces a kind of braking eifect, when this end during sliding movement of the follower leaves behind a very thin film on the inner wall of the reservoir and thus to some degree influences and regulates supply of ink at the writing or ball point end.

The film producing end layer of the follower mass should not be able to mix with any adjacent layer or layers of the remainder of the follower and must be of such consistency that at normal room temperature escape or flowing out along the wall of the reservoir will be effectively prevented. Silicon oil or grease, as well as mineral oil or grease as a follower mass is considered useful for such purpose.

It can thus be seen according to the invention that improved means are provided whereby the fluid or semipasty ink contained in fountain pens is protected from contact with the air and is at the same time prevented from flowing out through the air intake of the ink reservoir.

Thus, a lid or follower is slidably mounted within the ink reservoir adjacent the surface of the ink or paste contained therein. This lid or follower which may be a cylindrical body of small weight, for instance, a semipasty body of a composition of paraflin or may consist of a substance having approximately the same viscosity as the ink but of such nature that it is unable to mix therewith, is adapted to prevent the air admitted through the air intake to contact the surface of the ink and also to prevent the ink from flowing from the reservoir into the interior of the barrel.

Alternatively the lid or body may consist of a cylindrical body of resilient material, wax, paraffin or of a layer of a viscous or pulpy mass of substantially the same viscosity as the ink and having a color which is distinctly different from the color thereof, thereby providing means for indicating to the user when the ink reservoir is approaching exhaustion which will become apparent from the change of color on the writing paper, when the pulpy mass above the ink column is extracted through the ink feeding channel to the writing ball.

The ball tip fountain pen may comprise a pulpy mass within said reservoir and wherein said lid slidably mounted within the said reservoir is a layer of a pulpy mass which may have substantially the same viscosity as the pulp ink adjacent the surface thereof, said pulpy mass being of such nature that it is unable to mix with said ink.

Reverting again to FIG. of the aforesaid disclosure, the reservoir 70 which may be of capillary dimensions, if desired, may contain a main ink column 74 of conventional ball pen writing ink with an ink slug 75 which is in contact at 74a with said ink 74. Ink slug 75 may have a color distinctly different from that of the ink column 74, whereby ink slug 75 serves to indicate to the user that the pen is nearing exhaustion, and that a new reservoir of ink must be supplied to the fountain pen. When the ink of the ink column has been almost used up, the specially colored ink slug 75 (which may be of the same ink composition as ink column 74) will approach and make contact with the writing ball and will be transferred onto the writing paper to thereby provide the aforesaid indication.

Above ink slug 75 is then positioned a protective layer 76 made from any of the suitable follower substances hereinabove mentioned capable of protecting the ink slug 75 and ink column 74 against deterioration by air or other gaseous medium. It is, of course, understood that layer 76 may be of different dimensions and may be of shorter length than shown in FIG. 5. Protective follower or layer 76 may be, e.g., a greasy product derived from the distillation of petroleum, such as petroleum jelly, semipasty paraffin and like derivative having or affording the desirable properties (non-drying upon exposure to air, etc.) hereinabove set forth.

Likewise and for the same purpose as set forth hereinabove, plug member or layer 88 of FIG. 6 may consist '8 of ink of any suitable composition (oil base, water base, and the like), but differ in color from the ink constituting ink column 87, thus also indicating the exhaustion of the latter as soon as layer 88 reaches ball tip 85.

In this case, ink plug 88 must have a composition different from that of ink column 87 and must be substantially imiscible therewith. It also must be impervious to air or a gaseous medium to effectively protect the ink column 87.

It is to be noted that the ink plug may be a fluid or pasty substance, but of such composition that it will not readily mix with the ink, although such substance may have the same consistency as the ink of the ink column. Consequently, the plug may consist of a plastic or plasticized substance, having such characteristics that it can adjust itself to the form or cross section of the reservoir while it is sliding therein. For instance, the plug may consist of a spongy material impregnated with a substance which serves to reduce the friction between the plug and the wall of the reservoir. In any event the plug will not permit the ink in the reservoir to get in direct contact with the ambient air as the reservoir is vented.

To employ an ink plug which is only different in color from the remainder of the ink column with which the ink plug is to cooperate, would only be possible, if such ink plug would have the same high viscosity as that of the ink of the ink column, as otherwise the ink plug would quickly diffuse with the remainder of the ink column. Protection of ink plug and ink column of substantially the same high viscosity against influence from the ambient air may, however, not be attained, unless a further plug according to this invention is used, which is in contact with the first-mentioned ink plug, the latter functioning as an indicator for the user of the fountain pen to show that the remainder of the ink column is exhausted.

As an example of an ink in which the present invention finds particular utility, applicant has found that a glycolbased ink absorbs moisture from the air upon exposure to air and that such moisture causes the ink to harden or solidify. Therefore, a pen with a reservoir filled with such glycol-based ink Will cease writing because the exposed surface of the ink would harden to a solid mass and the ink could no longer flow. A plug follower formed from a mineral oil based ink serves to protect the glycol-based ink from exposure to air and prevent hardening thereof. The mineral-based ink is immiscible with the glycol-based ink and is not itself subject to hardening or other deterioration upon exposure to air. A suitable glycol-based ink has the following composition in parts by weight:

Triethylene glycol 100 Beta naphthol 32 Azosol Fast Black MA 12 Azosol Brilliant Blue B It will be readily apparent that other glycols, such as diethylene glycol, propylene glycol and other alcohols and polar solvents may be substituted wholly or in part for the triethylene glycol. The beta naphthol acts to solubilize the dyes to some extent. The Azosol dyes above specified are made by General Dyestuffs Corporation and are conventional type ink dyes. If desired, a detergent may be added to the ink to further assist in holding the dyes in solution and to impart smoother writing action to the ball. The oil-based ink may be a different color from the main body of ink, or it may be the same color to thereby increase the capacity of the pen.

It is important that the follower material is different from the ink not only in composition but also in nature. This also applies to the aforesaid adjoining layers of plugs. If, for instance, one follower plug consists of two distinctly colored layers of the same material, i.e., petroleum jelly, these layers would be different, but the difference would only be as to the colors of the dyestuffs, but the nature of both layers would be the same and they would, therefore, not be immiscible. According to the invention,

however, it is required that such layers be immiscible. If one of the layers consisted of petroleum jelly and the other of a vegetable oil substance, even if they had the same color and both were colored with the same dyestuif, they would be of different nature and composition, substantially immiscible with each other and serve the purpose of this invention.

The follower should be composed of such mass that it not only avoids commingling with the ink substance used, but should also prevent any dissolution of the latter; furthermore the viscosity of the follower mass must withstand to a marked degree exposure to tropical as well as to arctic climate, thus does not lose its capability of sliding within and readily following the end surface of the ink column and does not become so easily liquid or too viscous.

If the suction effect created during writing for the lowering of the level of the ink column is or becomes insufficient, the movement of the follower mass may be influenced by additional feed pressure, as hereinabove described with respect to FIGS. 3 and 4 and the follower mass must necessarily withstand such pressure.

In order to overcome any difliculty with respect to any colored deposit during lowering of the level of the ink column along the transparent wall of the reservoir, the follower is so dimensioned that the volume of the latter is equal to or even larger than the volume of the ink column, to be used up during the writing operation, whereby the upper end of the follower becomes discernible or viewable in the reservoir, thus avoiding that any part of the follower mass proper would leave any marking or indication on the paper to be written upon (FIG. 6).

The height of the follower may be chosen so that, if the wall of the reservoir is provided with several gradations extending between the level of the ink column when said reservoir is filled and a level of said column at which depletion of the ink column and complete emptiness of the reservoir occur, the latter or end gradation or marking must not necessarily be indicated at the limit point between ink and follower. It is, however, essential that the height of the follower or plug coincides with the distance of the upper level of the ink column from the inner end of the ball point when the ball point pen is completely filled (FIG. 5). It may become also important to observe whether the follower mass will leave any film deposit on the inner wall surface of the reservoir and such loss of follower mass must be compensated for by suitable increase of the height of the follower mass. The height or length of the follower or seal is at least & of the length of the ink column. It has been found that silicon oil or grease will contribute to elimination of such undesirable film deposits.

If the follower is composed of a plurality of layers, as hereinabove set forth, the uppermost layer thereof must be sufficiently long and also suitable viscous that the remainder of the follower as well as the ink will not flow out of the reservoir, even if the uppermost follower layer will leave fine film deposits on the reservoir wall.

In building up the follower in layer formation care may be taken to employ a lowermost, relatively thin layer on the follower for the purpose of preventing any influence of the ink on the follower mass during long storage and under extreme climatic conditions, as herein referred to.

The invention is not intended to be limited to the form shown, which is to be understood as illustrative only and not limiting, as various changes in construction and 10 arrangement may be made, all coming within the scope of the claims which follow.

In the forms of the invention employing an ink tube of larger than capillary dimensions, the device may be provided with any suitable means for preventing the liquid follower from flowing out away from the ink when the pen is tilted to other than writing position.

I claim:

1. An ink reservoir for a ball point fountain pen comprising an elongated tubular casing containing a column of writing ink, and a non-solid plug slidable along the wall of said reservoir and in contact with one end of said column, said plug consisting of at least two layers of different non-solid materials, the first layer adjacent the end of the ink column being substantially immiscible both with the ink of said column and with the adjoining layer, the next outermost layer being immiscible with said first layer, and being impervious to and non-hardening upon exposure to air and of such high viscosity that it is unable to flow out of said reservoir.

2. An ink reservoir as defined in claim 1 wherein said first layer comprises an ink of a different color from the color of said column of writing ink.

3. An ink reservoir for a ball point fountain pen comprising an elongated tubular casing containing a column of writing ink, and a non-solid plug slidable along the wall of said reservoir and in contact with one end of said column, said plug consisting of at least two layers of different non-solid materials, the first layer adjacent the end of the ink column being substantially immiscible both with the ink of said column and with the adjoining layer, the next outermost layer being immiscible with said first layer and including a cleaning agent for cleaning from the wall of said casing any film of ink adhering thereto and passing said first layer.

4. An ink reservoir as defined in claim 3 wherein said next outermost layer is of a material containing a solvent for said ink and needing protection from contact with air, and a third layer adjacent said next outermost layer and of a material impervious to and non-hardening upon exposure to air.

5. An ink reservoir for a ball point fountain pen comprising an elongated tubular casing containing a column of writing ink, and a non-solid plug slidable along the wall of said reservoir and in contact with one end of said column, said plug consisting of at least two substances of different non-solid materials, one being substantially immiscible both with the ink of said column and with the other substance, said other substance being a solvent for said writing ink said one substance being in contact with said one end of said column and between and in contact with said column of ink and said other substance.

References Cited in the file of this patent UNITED STATES PATENTS 551,540 Fowler Dec. 17, 1895 555,763 Fessenden Mar. 3, 1896 1,915,426 Kohler June 27, 1933 2,249,163 Nissen July 15, 1941 2,265,055 Biro Dec. 2, 1941 2,427,921 Pfaelzer Sept. 23, 1947 2,495,013 Martin July 17, 1950 2,678,634 Henriksen May 18, 1954 FOREIGN PATENTS 508,048 Belgium Jan. 15, 1952 

1. AN INK RESERVOIR FOR A BALL POINT FOUNTAIN PEN COMPRISING AN ELONGATED TUBULAR CASING CONTAINING A COLUMN OF WRITING INK, AND A NON-SOLID PLUG SLIDABLE ALONG THE WALL OF SAID RESERVOIR AND IN CONTACT WITH ONE END OF SAID COLUMN, SAID PLUG CONSISTING OF AT LEAST TWO LAYERS OF DIFFERENT NON-SOLID MATERIALS, THE FIRST LAYER ADJACENT THE END OF THE INK COLUMN BEING SUBSTANTIALLY IMMISCIBLE BOTH WITH THE INK OF SAID COLUMN AND WITH THE ADJOINING LAYER, THE NEXT OUTERMOST LAYER BEING IMMISCIBLE WITH SAID FIRST LAYER, AND BEING IMPERVIOUS TO AND NON-HARDENING UPON EXPOSURE TO AIR AND OF SUCH HIGH VISCOSITY THAT IT IS UNABLE TO FLOW OUT OF SAID RESERVOIR. 